Focal Lesions

1
Focal Lesions
2
Left Hemisphere Processing

• The left hemisphere plays a major role in the
  neural processes governing the production and
  comprehension of propositional (meaningful)
  language.
• For this reason, it has been designated the
  dominant hemisphere.
• It is well-suited to processing linguistic
  elements and information sequentially and
  analytically.
• Cortical representations of linguistic processes
  are not static nor are they subject to exact
  demarcations.
• Rather, language representation exists in
  functional fields within which specific abilities
  (modules) overlap with other linguistic and
  symbolic abilities.

3
Quick Review of Modules

• Very specific communication and cognitive
  abilities are localized in modules at different
  levels of synaptic connection.
• At the first synaptic level, sensation is mapped
  by finely tuned neurons into a primary dimension
  for vision, the dimension is retinotopic for
  audition, the dimension is tonotopic.
• The second synaptic level mediates the more
  differentiated extraction of specific attributes,
  such as color and motion frequency, intensity,
  and periodicity.
• Motivational, emotional, and attentional
  modulations are relatively weak at the first two
  synaptic levels.

4
Quick Review of Modules

• However, motivational, emotional, and attentional
  modulations become increasingly more influential
  at higher synaptic levels where they help to
  depict a version of the world based on
  significance rather than appearance.
• The third and fourth synaptic levels play
  critical roles in the perceptual encoding of
  faces, objects, words, and extrapersonal targets
  by ensembles of coarsely tuned neurons.
• The fifth and sixth synaptic levels are found in
  the heteromodal, paralimbic, and limbic regions
  of the cerebral cortex.
• These transmodal areas are critical for
  transforming perception into recognition, words
  into meaning, scenes and events into experiences,
  and spatial locations into targets for
  explorations.

5
Quick Review of Network Theory

• Transmodal areas constitute epicenters for
  large-scale distributed networks.
• All large-scale networks have similar
  organization they all have two interconnected
  epicenters.
• If one epicenter member of the pair is
  interconnected with additional cortical areas,
  then the other epicenter member is interconnected
  also with the same additional cortical areas.
• Consequently, if one epicenter transmits a
  message, the other epicenter will receive it
  directly from its pair, but also indirectly from
  the vantage point of the additional cortical
  areas.

6
Quick Review of Network Theory

• Language processing, then, is subserved by
  regions that form integrated cerebral networks
  based on neural intercommunications.
• The components of these networks can be divided
  into critical versus participating areas.
• Lesions which irreversibly impair performance in
  a cognitive domain help to identify network
  components that are critical for its integrity.
• Other areas may participate in the coordination
  of certain aspects of tasks in the same domain.

7
The Perisylvian Network

• The two epicenters of the language network are
  Brocas and Wernickes areas.
• Brocas area includes the premotor region (BA44)
  and the adjacent heteromodal fields of BA 45-47.
• Brocas area displays relative specialization for
  the articulatory, syntactic, and grammatical
  aspects of language.

8
The Perisylvian Network

• Wernickes area includes the posterior part of
  auditory association cortex in BA22 and its
  adjacent heteromodal fields in BA39-40 and
  perhaps BA21.
• Wernickes area displays a specialization for the
  lexical and semantic aspects.

9
The Perisylvian Network

• Additional components of this network are located
  in the striatum, thalamus, and the association
  areas of the frontal, temporal, and parietal
  lobes.
• Damage to this network in the left hemisphere of
  the majority of the population yields aphasia,
  alexia, and agraphia.
• Linguistic processes in the brain can be broadly
  divided into those that link thought (or meaning)
  to word forms (lexical-semantic) and those that
  sequence words and word endings to convey
  relationships among words (syntactic).

10
The Perisylvian Network

• Aphasia refers to a disturbance of either one of
  these components, reflected in abnormalities of
  oral or written communication.
• The classical aphasia syndromes are based on
  patterns of deficits in spontaneous speech,
  comprehension of oral and written language,
  repetition, naming, and writing.
• The aim of the language examination is to
  identify whether lexical-semantic or syntactic
  processes are primarily affected and also to
  categorize the aphasia according to the classical
  syndromes.

11
Left Hemisphere Lesions

• For over a century, people with brain damage have
  been recognized as displaying different
  combinations of symptoms related to specific
  areas of brain injury.
• When damage occurs in certain functional areas,
  such as the primary or association cortices, a
  specific kind of impairment in linguistic element
  processing may result.
• When damage is not discrete, as in cases of
  diffuse axonal injury, or large vessel
  infarctions, the resulting pattern of impairment
  often presents a mixture and overlap of symptoms.

12
Left Hemisphere Lesions

• Although we will utilize the term aphasia in
  connection with prototypic disturbances in
  language function, keep in mind that aphasia is
  an umbrella term encompassing a wide variety of
  language dysfunctions, on the receptive/comprehens
  ion and expressive/production continuum.
• We will also look at communication function
  within the left hemisphere along the horizontal
  organization continuum of the posterior to
  anterior regions.

13
Posterior Language Zones

• The posterior language zone in the dominant left
  hemisphere includes the middle and posterior part
  of the first, second, and third temporal gyri,
  Heschls gyrus, the inferior parietal lobule,
  including the supramarginal and angular gyri.

14
Posterior Language Zones

• The nuclear region of the posterior language zone
  is situated in the posterior part of the first
  temporal gyrus (unimodal Wernickes area) and in
  the adjacent areas of the middle first temporal
  gyrus, Heschls gyrus, the posterior portion of
  the second temporal gyrus, and the angular gyrus.

15
Posterior Language Zones

• In the syndromes of posterior aphasia, the
  following characteristics are frequently present
• addition of functional words in expressive
  speech
• disturbances of phrase comprehension
• alienation of word meaning
• disorders of naming
• semantic and phonemic paraphasias
• decreased awareness of verbal expression errors
• problems with auditory phoneme and word
  comprehension
• sensory aprosody and
• increased speech activity.

16
Areas of Linguistic Processing Impairments

• The superior temporal gyrus is the site of
  auditory input language interpretation.
• Damage to this area makes for difficulty
  discriminating speech sounds, distinguishing
  syllables/words which sound familiar, analyzing
  words into component sounds, or resynthesizing
  them.

17
Superior (1st) Temporal Gyrus

• Words become vague and undifferentiated,
  affecting comprehension.
• Expressively, language is empty, frequently
  circumlocuted, and littered with semantic
  paraphasias.
• Neologisms for nouns and verbs are common.
• A module for auditory sequential memory is
  thought to reside just lateral to Heschls gyrus.
• Word repetition may be made difficult by
  instability of retained auditory sequences

18
Angular Gyrus (Area 39)

• The angular gyrus, at the juncture of the
  temporal, parietal, and occipital lobes, is
  thought to be the module site for word meaning.
• A lesion to this area disturbs naming and
  alienates word meaning for body parts and
  space-time relationships.
• With lesion extension into the occipital and
  parietal areas, alexia and agraphia may result.

19
Supramarginal Gyrus (Area 40)

• The supramarginal gyrus, found curving around the
  lateral sulcus, is thought to be the module site
  for abstraction and integration of sensory
  information necessary for naming.

20
Supramarginal Gyrus (Area 40)

• A lesion in this area produces phonological
  processing errors, called phonemic paraphasias,
  in contextually appropriate lexical items in the
  form of substitutions (dite/kite), deletions
  (reen/green), and transpositions (predesent/
• president).

21
Anterior Language Zone

• The anterior language zone in the dominant left
  hemisphere includes the posterior part of the
  third frontal gyrus, also known as Brocas area,
  the lateral operculum, the insula, and the
  posterior part of the first and second frontal
  gyri.

22
Anterior Language Zone

• On the mesial surface of the left hemisphere,
  this zone includes the supplemental motor area
  and the anterior cingulate gyrus.

23
Anterior Language Zone

• Syndromes of anterior aphasia are generally
  characterized by
• telegraphic style, with a predominance of
  substantive words
• lack of grammatical functor words
• impoverishment of speech, reduced to short
  phrases and high-frequency words
• relatively preserved comprehension and naming.
• In anterior aphasia, motor elements are present
  and consist of deformation of articulation, motor
  dysprosody, aphonia, hypophonia, and decreased
  speech activity.

24
Brocas Area (44)

• Delineated as a premotor zone in the inferior
  (3rd) frontal gyrus, Brocas area is the module
  site thought to program the oral and phonatory
  mechanism for speech movements.
• A lesion in this area would likely produce
  phonetic-articulatory sequencing deficits in
  syntactically normal utterances, evidencing motor
  dysprosody and perseverations.

25
Premotor Gyrus (Area 6)

• A lesion in the left premotor gyrus may result in
  a nonfluent aphasia characterized by strings of
  content words, lacking grammatical functors
  (agrammatism).
• Impaired prosody is usually reflected in a
  tendency to drop unstressed syllables,
  inflections, and auxiliaries.

26
Supplemental Motor Area (Area 8)

• A lesion in the supplemental motor area, located
  in the medial frontal cortex, may result in
  partial mutism initially, eventually resolving to
  some spontaneous speech, some repetition, and
  naming.
• Difficulty initiating spontaneous speech usually
  prevails.

27
Anterior Cingulate Gyrus (Area 24)

• Bilateral damage to the anterior cingulate gyrus
  results in akinetic mutism, with no evidence of
  preserved language comprehension.
• With recovery, speech returns through aphonic
  whispering and hoarseness.
• Aphasia and motor speech components are absent.

28
Mixed Anterior-Posterior Zones

• Lesions can involve aspects of both anterior and
  posterior language zones.
• Salient symptoms of mixed aphasia include loss of
  expressive speech, graphic, and gestural output,
  and a noticeable lack of auditory comprehension.
• This is an apparently global aphasia.

29
Right Hemisphere Processing

• The right hemisphere is preferentially devoted to
  processing of stimuli characteristics related to
  visuo-spatial, bodily, and affective domains.
• Damage to the right hemisphere results in some of
  the most bizarre and complex syndromes observed
  in clinical medicine.
• Visual hallucinations, denial of illness,
  unilateral neglect, amnesia for nonverbal
  material, and loss of speech prosody are among
  the unusual usual symptoms exhibited by clients
  with RH injury.
• Direct categorization of clinical syndromes by
  specific modules/regions is difficult because
  there is frequent regional overlap of network
  components.
• Instead, disorders are categorized by the
  underlying neuropsychological processing
  abnormalities.

30
Right Hemisphere Networks

• There are a number of different networks that can
  found within the right hemisphere
• a right-hemisphere spatial attention network with
  epicenters in the dorsal posterior parietal
  cortex, the frontal eye fields, and the cingulate
  gyrus
• a right-hemisphere face and object recognition
  network with epicenters in the middle temporal
  gyrus and the temporal pole and
• a prefrontal network involved in working memory
  and executive function.

31
Dorsal Parieto-frontal Network

• The spatial orientation network consists of three
  interconnected cortical epicenters around the
  intraparietal sulcus, the frontal eye fields, and
  the cingulate gyrus.

32
Dorsal Parieto-frontal Network

• The parietal component is specialized for the
  perceptual representation of behaviorally
  relevant locations and their transformation into
  targets for attentional actions.
• It receives many and various inputs including
  visual, auditory, somaesthetic, limbic and motor
  output signals.

33
Dorsal Parieto-frontal Network

• The frontal component, the frontal eye fields
  (FEF), are located along the superior lateral
  convexity.
• The FEFs coordinate and maintain eye and head
  movements, gaze shifts, and thus orienting and
  attentional reactions in response to
  predominantly visual, but also tactile and
  auditory stimuli.

34
Dorsal Parieto-frontal Network

• It is also involved in focusing attention on
  certain regions within the visual field, as well
  as in making smooth pursuit movements and perhaps
  guiding eye movements while reading and when
  writing.
• The cingulate gyrus has a specialized role in the
  distribution of effort and motivation.

35
Dorsal Parieto-frontal Network

• The anterior portion is thought to engage in
  global attention.
• The posterior part is thought to participate in
  differentiated lateralized shifts of motivational
  relevance and focalized attention.

36
Dorsal Parieto-frontal Network

• Damage to this network in the right hemisphere
  yields deficits of spatial attention and
  exploration.
• Contralesional hemispatial neglect occurs almost
  exclusively after right-sided damage to this
  network and is characterized by the reduction of
  neural responses that can be mobilized by sensory
  events located on the left and by motor plans
  directed to the left.
• When neglect is severe, the patient may behave as
  if one-half of the universe had abruptly ceased
  to exist in any meaningful form (Mesulam, 2000).

37
Dorsal Parieto-frontal Network

• Damage to this network in the right hemisphere
  yields deficits of spatial attention and
  exploration called hemispatial neglect
• It is characterized by the reduction of neural
  responses that can be mobilized by sensory events
  located on the left and by motor plans directed
  to the left.
• When neglect is severe, the patient may behave as
  if one-half of the universe had abruptly ceased
  to exist in any meaningful form (Mesulam, 2000).

38
Dorsal Parieto-frontal Network

• When both the right and left sides of the
  occipito-parietal cortex is damaged, this pattern
  of damage often results in Bálints syndrome, an
  acquired disturbance of the ability to perceive
  the visual field as a whole.
• Holistic visual field perception is affected by
  the inability to perceive more than one object at
  the same time (simultanagnosia), which is
  accompanied by an impairment of target pointing
  under visual guidance (optic ataxia) and an
  inability to shift gaze at will toward new visual
  stimuli (ocular apraxia).

39
Dorsal Parieto-frontal Network

• Such patients are essentially blind outside the
  focus of their attention, and cannot locate,
  reach for, or track the spatial movements even of
  items that are within their focus of attention.
• In some ways, this represents the complete
  dissolution of spatial awareness which Balint
  described "as if there is no there, there."

40
Ventral Occipito-temporal Network

• The transmodal epicenters for the face and object
  recognition network are located in the middle
  temporal gyrus and the temporal pole.
• Additional critical components are located in the
  fusiform gyrus and the inferior temporal gyrus.

41
Ventral Occipito-temporal Network

• Damage to this network yields recognition
  deficits such as object agnosia and
  prosopagnosia, agnosia for faces.
• The lesions that cause such deficits are almost
  always bilateral.
• The fusiform gyrus is the most common site of
  lesions, probably because it is the only part of
  this network with a vascular supply that makes
  bilateral damage likely.

42
Prefrontal Network

• The prefrontal heteromodal and orbitofrontal
  cortices are the major epicenters involved in the
  coordination of comportment.
• The prefrontal heteromodal cortex and the
  posterior parietal cortex provide epicenters for
  a network involved in working memory and related
  executive functions.

43
Prefrontal Network

• Deficits of comportment are more frequently
  associated with a lesion of the orbitofrontal and
  adjacent medial frontal cortex.
• Deficits of executive function and working memory
  are more frequently associated with damage to the
  dorso-lateral prefrontal cortex.
• Clinically significant deficits are usually seen
  only after bilateral lesions.
• Unilateral right-sided lesions can give rise to
  behavioral disinhibition.

44
Right Hemisphere Impairments

• The formal linguistic components of communication
  are enhanced and modified by facial expressions,
  gestures, body posture, speech prosody, and other
  paralinguistic signals.
• Right-sided cerebral lesions may result in
  specific deficits in the comprehension and
  production of both affective and emphatic prosody
  and with the nonverbal identification of facial
  affect.
• They may also interfere with the ability to
  adjust interpersonal behavior to social context,
  such as turn-taking, style switching to fit
  audience, and maintaining appropriate
  interpersonal distance.

45
Right Hemisphere Impairments

• Complex perceptual and spatial processing is
  needed for constructions, dressing, and spatial
  distribution of attention.
• Constructional abilities entail complex
  perceptual, motor, and executive functions
  required by tasks such as drawing, assembling
  puzzles, and constructing designs from blocks or
  sticks.
• In construction, the right hemisphere is thought
  to maintain the overall configuration of the
  design, whereas the left hemisphere is thought to
  process internal detail.

46
Right Hemisphere Impairments

• Patients with right hemisphere lesions may employ
  a piecemeal or disorganized approach to
  construction tasks, overlooking the large
  picture.
• Impairments of the ability to dress oneself can
  take different forms.
• With right hemisphere posterior parietal lobe
  lesion, the difficulty may be confined
  exclusively to dressing the left side of the
  body, possibly due to hemispatial neglect.
• A more generalized dressing apraxia has to do
  with the inability to align the axis off a
  garment with the body axis.

47
Right Hemisphere Impairments

• Deficits associated with occipital lobe damage
  include disorders of color perception, disorders
  of visual processing, and disorders of
  visuo-verbal processing.
• Deficits associated with parietal lobe damage
  include difficulty recognizing visuospatial
  information, impaired recognition of objects in
  unfamiliar views, and difficulty with spatial
  orientation.
• Other deficits associated with right parietal
  damage include difficult sustaining attention,
  hemispatial neglect on the side contralateral to
  the lesion, unawareness or denial of deficits,
  and difficulty with orientation and location in
  space.

48
Right Hemisphere Impairments

• Difficulties associated with right temporal lobe
  damage include deficits in processing music and
  deficits in nonverbal memory.
• Deficits associated with frontal lobe damage
  include difficulty with planning and
  problem-solving, decreased behavioral initiation
  and spontaneity, distractibility, perseveration,
  and poor memory for order of sequence of events.

49
Occipital Lobe Damage

• Lesions to the occipito-parietal and
  occipito-temporal areas produce a variety of
  visual processing difficulties.
• Prosopagnosia, or agnosia for faces, is an
  acquired deficit in the recognition and
  identification of previously known and familiar
  human faces (e.g., Oliver Sacks The Man Who
  Mistook His Wife for a Hat).
• Patients have adequate visual acuity, but they
  are unable to recognize or identify family,
  friends, famous persons, or even their own
  reflection in a mirror.

50
Occipital Lobe Damage

• If the disorder is severe, patients may be unable
  to distinguish between male and female, human and
  animal, and young and old faces.
• They often recognize people known to them by
  their voice, clothing and accessories, body size,
  hair color, or gait.
• Topographagnosia, or environmental agnosia, is
  the acquired loss of the ability to recognize
  visual stimuli relating to a persons
  environment.
• The environment is perceived as different,
  unfamiliar, or unrecognizable.
• The person has trouble finding his/her room,
  home, locating public buildings in a specified
  area, or drawing a map of how to get to a
  specific location.

51
Occipital Lobe Damage

• A lesion to the inferior visual association
  cortex, in the absence of retinal pathology,
  results in achromatopsia, an acquired disorder of
  color perception, characterized by a loss of
  color vision in all or part of (quadrant or
  hemifield) the visual field.
• Lesions in the right occipital cortex also can
  produce reading problems that arise from gaze
  instability, spatial neglect, or other defects in
  visual processing, as opposed to more
  linguistically based disorders of reading.

52
Occipital Lobe Damage

• Hemialexia, the loss of reading ability in one
  visual hemifield, may occur in the RH patient
  with severe neglect.
• The left side of words or sentences may be
  neglected with varying degrees of awareness.
• The majority of reading problems that occur as
  sequelae of right hemisphere injury are derived
  form some combination of visual processing
  deficits, including visuo-perceptual,
  visuo-spatial, and/or visuo-verbal decoding
  difficulties.

53
Parietal Lobe Damage

• A salient feature of RH syndromes is a group of
  related disorders characterized by deficits in
  corporeal awareness.
• Patients experience impaired awareness of self
  and alterations in their body image, ranging from
  uncritical underestimation to explicit,
  intractable denial of phenomena.
• Autopagnosia is the inability to indicate various
  parts of the body, either by pointing to them on
  command, naming them, or matching them to
  pictures or parts on the examiners body.

54
Parietal Lobe Damage

• Anosodiaphoria is a term first coined by Babinski
  in reference to the lack of concern shown by
  patients with hemiplegia.
• Although aware of their paralysis, some patients
  exhibit carefree indifference and inadequate
  insight as to the implications/consequences of
  the condition.
• Unilateral neglect is a syndrome in which the
  ability to direct attention to important events
  in one half of personal and extrapersonal space
  is compromised.
• The patient fails to attend to, respond to, or
  report stimuli in that hemispace.
• Motor, sensory, visual, and auditory modalities
  can be affected.

55
Parietal Lobe Damage

• Asomatognosia refers to the feeling of
  nothingness described by some patients with
  hemiplegia who report they feel the limb is
  missing or that there is nothing to the left of
  midline of the body.
• Hyperschematia refers to a disorder in which the
  patient feels as though the affected appendages
  are swollen or heavy.
• Some have referred to these appendages as dead
  wood or dead meat.
• Misoplegia is hatred of the paralyzed limb.
• Personification refers to the attempt by the
  patient to name or otherwise anthropomorphize the
  affected limb, treating it as another person.

56
Parietal Lobe Damage

• Somatoparaphrenia refers to a paranoid reaction
  to the paretic limb, specifically the belief that
  the paretic limb has undergone some sort of
  horrid transformation by some mechanical
  manipulation.
• Supernumerary phantom refers to a condition in
  which the patient imagines that there is an extra
  or third limb on the affected, hemiplegic side,
  which is not in the position in space where the
  actual limb lies.
• These additional limbs are often reflected in
  patient drawings.
• Denial syndromes are also common with parietal
  lobe damage.
• Denial involves negation or refusal to accept a
  disability or condition it can be explicit or
  implicit.

57
Parietal Lobe Damage

• Explicit denial ranges from minimization and
  temporal displacement of the disability to
  complete denial or projection of the disability
  outside the self.
• Example 1 A man with a self-inflicted gunshot
  wound to the head which penetrated the brain
  attempted to explain his skull fracture and
  subsequent hospitalization by stating that he had
  tripped over the cat and hit his head on a gulf
  ball.
• Example 2 A woman with a right CVA and severe
  left hemiplegia stated that she was in the
  hospital for the examiners wedding and was just
  resting until the ceremony began.

58
Parietal Lobe Damage

• Implicit denial involves disinterest in,
  inattention to, or lack of reaction to the
  paralyzed side of the body.
• The individual may fail to dress that side of the
  body or respond to threatening or painful stimuli
  on that side of the body.
• Disorders of praxis are disorders of learned
  movement that cannot be adequately explained on
  the basis of attentional deficits, weakness of
  musculature, sensory loss, or comprehension
  deficits.
• Common with right posterior or parietal lobe
  lesions are dressing apraxia and constructional
  apraxia.

59
Parietal Lobe Damage

• Dressing apraxia is an impairment in the ability
  to dress oneself due to complex visuospatial
  deficits and sequencing difficulties.
• Body-garment disorientation is characterized by
  the inability to orient ones body part to the
  appropriate garment or portion of the garment to
  accomplish the logistics of dressing.
• The garment may be turned backwards out or inside
  out, and/or the left and right may be inverted or
  the up and down.
• Constructional apraxia is manifested as a
  difficulty in putting together one-dimensional
  units so as to form two-dimensional figures or
  patterns.

60
Parietal Lobe Damage

• People with this disorder do not have difficulty
  making most types of skilled movements with their
  arms and hands.
• They have no trouble using objects properly,
  imitating their use, or pretending to use them.
• The primary deficit in constructional apraxia
  appears to involve the ability to perceive and
  imagine geometrical relations.

61
Parietal Lobe Damage

• The defect can be seen in copying a visually
  presented object or design, assembling block or
  stick patterns, or in free drawing.
• Because of this deficit, a person cannot draw a
  picture, say, of a cube, because he/she cannot
  imagine what the lines and angles of a cube look
  like, not because of difficulty controlling the
  movements of his or her arm and hand.

62
Loss of Hemispheric Integrity

• Various disorders of language processing, general
  behavior and psychic integrity, and visual
  symbolic processing arise when the right
  hemisphere is damaged and there is loss of
  bihemispheric integrity.
• Right hemisphere damage can affect the following
  language processing skills prosody, affective
  language, integrative appositional language and
  pragmatics.
• Although the experience of emotion is mediated by
  the limbic system, a system with bilateral
  representation, expression of both emotion in the
  voice and face and the perception of emotion in
  voices and faces is dependent upon lateralized
  right hemispheric mechanisms.

63
Loss of Hemispheric Integrity

• Right-sided lesions can impair speech prosody
  without altering the propositional content of
  verbal output.
• Specifically, a lesion in the right frontal and
  anterior parietal area may result in a patient
  demonstrating good comprehension of speech
  prosody, but impaired spontaneous and imitative
  prosody.
• In patients in whom the lesion affects only the
  parietal area, comprehension of prosodic speech
  elements may be lost, but not the propositional
  content of language.
• Such patients may also have difficulty with
  imitative prosody.

64
Loss of Hemispheric Integrity

• Because the right hemisphere processes language
  more holistically than the left hemisphere,
  damage to the right hemisphere may cause problems
  in utilizing context to extract the main point or
  moral of a story, or to draw inferences, in spite
  of the fact that the ability to recall isolated
  details may be preserved.
• Right hemisphere injured individuals may also
  have problems interpreting abstract and
  figurative language, such as proverbs, idioms,
  and metaphors.
• Typically, they render a more concrete and
  literal interpretation of abstract language.

65
Loss of Hemispheric Integrity

• Comprehension of humor also appears impaired.
• Individuals with pre-central right hemisphere
  lesions demonstrate more exaggerated responses to
  humor, while individuals with post-central
  lesions demonstrate an overall flattened
  response.
• Inappropriate use of humor or off-color remarks
  in conversation is also frequently noted.
• The conversational style of RH individuals has
  been characterized as verbose and tangential.

66
Loss of Hemispheric Integrity

• Frequently, insignificant details and
  inappropriate personal remarks, and knowledge
  presupposition accompany the verbosity.
• Individuals may also have difficulty organizing
  and ordering information, and making a point in
  conversation.
• In addition to problems with organizing
  information, individuals with RH injury often
  have difficulty with the social uses of language
  interaction.

67
Loss of Hemispheric Integrity

• Some areas in which pragmatic disturbances are
  evidenced include proxemics, use of gesture,
  question formulation, comment interjection,
  assertion, requesting, conversational initiation,
  especially of a novel topic, topic change, topic
  selection, topic maintenance, turn-taking, repair
  and revision, and judging pause time between
  turns and interrupting.
• The quality of verbal and non-verbal feedback to
  the speaker may also be impaired, e.g., eye
  contact.
• They may be perceived as rude by family
  members, friends, and staff as the result of
  their lack of impulse control and social
  appropriateness, characterized by such things as
  undue familiarity, talking excessively, and
  violating the polite rules of conversation.

68
Loss of Hemispheric Integrity

• Alterations in sexual behavior and sexual
  function including inappropriate sexual advances
  and lewd comments have been noted in patients
  following RH injury.
• Altered sexual behavior may range from open
  masturbation, exposure, and overt verbal and
  physical sexual advances toward staff members to
  delusions with sexual content and confabulations
  concerning sexual activity.
• Some of these individuals may become preoccupied
  with body functions, such as bowel and bladder
  control, and may insist on receiving a physical
  means of expression, such as touch, from their
  caregivers.

69
Loss of Hemispheric Integrity

• Weinstein and Kahn (1955) described the case of a
  63-year-old woman with left homonymous
  hemianopsia, left astereognosis, reduced
  two-point discrimination, position sense, and
  point location in the left hand, right-left
  discrimination problems, dressing apraxia,
  topographic disorientation, and left neglect
  secondary to thrombotic obliteration of the
  middle cerebral artery.
• She was delusional and thought the man visiting
  her roommate was a mechanical dentist.

70
Loss of Hemispheric Integrity

• In her conversation with the examiner, she
  stated, Do you mind if I bother you?well, I
  like to be hot and bothered. Im propositioning
  you. I havent been hot and bothered for a long
  time.
• The same patient remarked that her roommate was
  noisy because she wanted to be laid.
• Reportedly, the patient exposed herself
  constantly and had to be placed in restraints due
  to frequent picking of her anus and genital area.

71
Loss of Hemispheric Integrity

• Disturbance of mood is also common with right
  hemisphere injury.
• Flatness or indifference reaction (indifference
  to or minimization of symptoms) is seen in most
  patients with only minor right hemisphere injury
  in contrast to the emotion-laden catastrophic
  reactions of left brain injured patients.
• Depression is difficult to diagnosis in RH
  individuals because of external affective
  disturbances (i.e., sad-looking face, vocal tone,
  flat affect).
• The individual may actually harbor a full
  component of concern, even to the extent of
  suicidal depression, without being able to
  physically express it.

72
Loss of Hemispheric Integrity

• Conversely, the patient may appear depressed
  because of the depressed affect, but not be
  experiencing depression.
• Some RH individuals may experience agitated
  confusion, delirium, disorientation, and various
  psychotic states.
• Agitated confusion is characterized by incoherent
  thought patterns, severe reduction in attention
  span, extreme distractibility, restlessness,
  disruption of goal-directed behavior,
  disorientation, and sometimes violent outbursts.
• Psychotic symptoms can include hallucinations and
  paranoid delusions.
• These symptoms may pass in a few days or, in some
  cases, may last for months.

73
Loss of Hemispheric Integrity

• Although rare, several specific delusions have
  been associated with RHD.
• Together they can be called misidentification
  syndromes.
• These include misidentification of place,
  persons, or body parts.
• Often these delusions occur in isolation without
  other symptoms of confusion.
• Misidentification of persons and place, or
  reduplicative paramnesia, results in patients
  thinking that familiar persons or places have be
  duplicated.

74
Loss of Hemispheric Integrity

• With misidentification of place, they may
  recognize that they are in a hospital, but
  confuse it with a hospital they were in
  previously.
• They may think they are in their bedrooms at home
  or that the hospital is attached to their houses,
  etc.
• Misidentification of persons or Capgras syndrome,
  refers to the delusion that others, but not the
  self, have been replaced by doubles.
• Typically, people with Capgras syndrome consider
  the duplicates or doubles as dangerous or
  frightening.

75
Loss of Hemispheric Integrity

• Another form of misidentification of persons is
  Fregoli syndrome.
• This form of misidentification involves the
  delusion that the known person is changing his
  appearance dramatically.
• For example, a RHD patient was convinced that the
  woman in the bed next to her was her husband, and
  that he was flirting with the nurses.
• She became angry and confused when her actual
  husband came to see her on his daily visits.

76
Summary of RHD

• Patients with RHD can have a variety of deficits,
  some of which can affect communication and
  cognition directly, and some of which exert
  indirect effects on the ability to participate in
  communicative events and to interact successfully
  with the environment.
• Just as not all adults with damage to the LH are
  aphasic, not all RHD adults have problems in
  perception, cognition and/or communication.
• The typical RHD patient almost always
  communicates adequately in superficial
  conversation.

77
Summary of RHD

• There may be a flatness in the voice and affect
  and a general sense of reduced arousal, but as
  long as the conversation is brief and covers
  familiar territory, one might not detect any
  communication deficits.
• Problems begin to emerge in more extended and
  complex conversation.
• Patients may seem disinterested and somewhat
  insensitive as communicative partners.
• They may begin and end conversations abruptly,
  fail to follow social conventions, and even
  appear rude.

78
Summary of RHD

• They may interrupt and fail to make eye contact.
• If they are no longer interested in what someone
  is saying, they may turn without apology to
  something else, apparently unaware of the
  disruption to the conversational flow.
• They may be perfunctory, making the least
  effortful response to questions, regardless of
  the consequences of their answers.
• Alternately, they may be verbose and rambling.
• They may have trouble getting to the point.

79
Summary of RHD

• Their discourse may seem to be made up of an
  assembly of facts without the glue that holds
  them together in an overriding structure.
• They may be led by internal associations to
  related but tangential issues, as if they are
  thinking out loud, rather than having a
  conversation.
• As listeners, they may focus on bits of
  information in a piecemeal way without
  integrating them into the larger picture.

80
Summary of RHD

• They may fail to respond to situational variables
  that specify the nature of the communicative
  eventlighthearted banter, serious discussion,
  superficial social exchange.
• They may have problems recognizing when people
  are kidding, sarcastic, or ironic.
• Patients with RHD may appear distant, remote,
  bound up in themselves.
• They may have trouble adopting other peoples
  point of view, or recognizing what their
  listeners know and what they do not know.

81
Summary of RHD

• The may show little appreciation for shared
  knowledge and may not take contextual variables
  into consideration.
• Vague references to unfamiliar people, places,
  and events, may force the listener to make the
  connections that have been omitted.
• Their capacity to attend may be reduced or fade
  in and out so that they miss crucial information.
• They may have trouble interpreting others
  intended meanings, and have difficulty conveying
  their own.
• They may have difficulty following the gist of a
  conversation, written narratives, television
  news, etc., if the information is presented too
  quickly or when the core concepts are subtle and
  require high levels of inference.

82
Summary of RHD

• Failure to admit to confusion and uncertainty can
  accompany reduced insight about physical and
  cognitive problems.
• Denial of deficit or denial of illness often
  gives the impression that RHD patients are
  unconcerned about their current status and future
  adjustments.
• Failure to respond appropriately to their
  deficits is characteristic of patients who have
  left-neglect.
• These patients may not notice their left arm
  dragging in their wheel chair spokes.
• They may not attend to people, events, or even
  sounds to their left.

83
Summary of RHD

• If patients have diffuse RHD, affective
  disturbances such as agitated confusion and
  certain types of delusions may be apparent.
• Patients with more focal RHD who are not
  otherwise confused may confabulate elaborate
  justifications to cover for cognitive
  uncertainty.
• It can occur as they try to negotiate information
  that is conflicting, ambiguous, makes no sense to
  them, and/or makes no sense to others.
• Rather than questioning, reflecting, analyzing,
  or dismissing it, they construct elaborate
  explanations to justify it, as if all must be
  right with the world or something may be wrong
  with them.

84
Summary of RHD

• Finally, patients with RHD may appear
  unresponsive to the emotional tone of the
  exchange and may have problems conveying their
  own emotions through prosody, facial expression,
  gesture, and body language.
• Their speech may be flat and uninflected.
• Their words may be embedded in some sort of
  stereotypic prosodic pattern that does not
  differentiate well among sentence types or
  emotional content, making listening difficult.
• Some patients, because of the size and/or site of
  their lesions, or because of the way their
  particular brains are wired, may be almost free
  of these signs.

85
Summary of RHD

• Among those that do have cognitive and
  communicative deficits, there is a range of
  impairment.
• Communication disorders may be obvious or subtle,
  however for the listener, there is a sense of
  someone using language, but not as effectively as
  expected.
• In other words, there is a sense that someone is
  communicating, but not quite connecting.